Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
An upgoing toe response in lower primates is not precluded by<br />
differences in peripheral anatomy: the extensor hallucis longus muscle is<br />
comparable with that in humans (Howell and Straus, 1961). Whether<br />
normal animals never show an upgoing hallux is somewhat controversial:<br />
incidental reports of Babinski signs in monkeys come from Collier (1899),<br />
Kalischer (1899), Rudolf (1922) and Tower (1940), whereas Fulton and<br />
Keller (1932) never found it in over one hundred monkeys and apes,<br />
comprising twelve species. Fulton and Keller also carried out a comprehensive<br />
study of changes of the plantar response after surgical lesions at<br />
different levels in the central nervous system. In macaques, the only<br />
operation capable of producing a unilateral upgoing toe response was<br />
hemisection of the thoracic spinal cord (later, Forster and Campbell (1942)<br />
found it after extensive and bilateral cerebral lesions, and Mettler ( 1944)<br />
after various brain ste1n coagulations). Fulton and Keller contrasted the<br />
extensive lesions which were necessary in macaques with the results in apes<br />
(chimpanzee, gibbon), in which ablation of the contralateral cortical 'leg<br />
area' was sufficient to cause a pathological plantar response; baboons<br />
occupied an intermediate position. They concluded that control of the<br />
plantar reflex moved increasingly cephalad as the primate scale was<br />
ascended, and that it had become a purely pyramidal function in apes.<br />
Kennard and Fulton (193 3) restricted the motor cortex associated with<br />
the Babinski sign in chimpanzees to area 4 (ablations of area 6 alone could<br />
be followed by a temporary fan sign - an unconfirmed finding).<br />
However, even selective ablations of the motor cortex probably involve<br />
descending connections other than the corticospinal system (Kuypers,<br />
1973 ). An exclusive lesion is possible only by medullary pyramidotomy.<br />
Sarah Tower (1940) performed this operation in chimpanzees and<br />
afterwards observed a Babinski sign on the contralateral side. We can<br />
safely conclude from this that, at least in apes, pure pyramidal tract lesions<br />
may cause a Babinski response.<br />
In man, reports of 'isolated' lesions of the corticospinal system resulting<br />
in a contralateral Babinski sign ·were, until recently, confined to its<br />
supramedullary course: the motor cortex (Walshe, 1935), the internal<br />
capsule (Fisher and Curry, 1965: Englander et al., 1975), and the cerebral<br />
peduncle (Bucy et al., 1964). This evidence could not be regarded as<br />
conclusive, because the corticospinal fibres are, at these levels, closely<br />
related to cortical projections on brain stem nuclei. Some, like Walshe<br />
( 1947), took a fatalistic attitude: 'disease and injury in man do not provide<br />
us with clean sections of the medullary pyramids'. This has proved to be a<br />
premature conclusion: of late, two case histories have been published that<br />
describe a Babinski sign after an almost pure lesion (infarction) of the<br />
contralateral pyramid (Chokroverry et al., 1975: Leestma and Noronha,<br />
19761<br />
114
Change language